Histology of type 3 macular neovascularization and microvascular anomalies in treated age-related macular degeneration: a case study

Objective/Purpose To investigate intraretinal neovascularization and microvascular anomalies by correlating in vivo multimodal imaging with corresponding ex vivo histology in a single patient. Design A case study comprising clinical imaging from a community-based practice, and histologic analysis at a university-based research laboratory (clinicopathologic correlation). Participants A white woman in her 90’s treated with numerous intravitreal anti-vascular endothelial growth factor (VEGF) injections for bilateral type 3 macular neovascularization (MNV) secondary to age-related macular degeneration (AMD). Intervention(s)/ Methods Clinical imaging comprised serial infrared reflectance, eye-tracked spectral-domain optical coherence tomography (OCT), OCT angiography, and fluorescein angiography. Eye tracking, applied to the two preserved donor eyes, enabled correlation of clinical imaging signatures with high-resolution histology and transmission electron microscopy. Main Outcome(s) and Measure(s) Histologic/ ultrastructural descriptions and diameters of vessels seen in clinical imaging. Results Six vascular lesions were histologically confirmed (type 3 MNV, n=3; deep retinal age-related microvascular anomalies (DRAMA), n=3). Pyramidal (n=2) or tangled (n=1) morphologies of type 3 MNV originated at the deep capillary plexus (DCP) and extended posteriorly to approach without penetrating persistent basal laminar deposit. They did not enter the sub-retinal pigment epithelium (RPE)-basal laminar space or cross Bruch’s membrane. Choroidal contributions were not found. The neovascular complexes included pericytes and non-fenestrated endothelial cells, within a collagenous sheath covered by dysmorphic RPE cells. DRAMA lesions extended posteriorly from the DCP into the Henle fiber and the outer nuclear layers, without evidence of atrophy, exudation, or anti-VEGF responsiveness. Two DRAMA lacked collagenous sheaths. External and internal diameters of type 3 MNV and DRAMA vessels were larger than comparison vessels in the index eyes and in aged normal and intermediate AMD eyes. Conclusions Type 3 MNV vessels reflect specializations of source capillaries and persist during anti-VEGF therapy. The collagenous sheath of type 3 MNV lesions may provide structural stabilization. If so, vascular characteristics may be useful in disease monitoring in addition to fluid and flow signal detection. Further investigation with longitudinal imaging before exudation onset will help determine if DRAMA are part of the type 3 MNV progression sequence. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by Genentech/ Hoffman LaRoche, The Macula Foundation, Inc., New York, NY; unrestricted funds to the Department of Ophthalmology and Visual Sciences (UAB) from Research to Prevent Blindness, Inc., and EyeSight Foundation of Alabama. AB reports grants from the Dr. Werner Jackstaedt-foundation. DC was supported in part by a studentship from Fundacao Luso-Americana para o desenvolvimento (FLAD, USA R&D@PhD, Proj 2020/0140). Purchase of the slide scanner was made possible by the Carl G. and Pauline Buck Trust. The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Approval for this study was obtained by Institutional review at the University of Alabama at Birmingham (protocol #300004907). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors * AMD : age-related macular degeneration BLamD : basal laminar deposit BrM : Bruch’s membrane ChC : choriocapillaris Ch : choroid DCP : deep capillary plexus DRAMA : deep retinal age-related microvascular anomalies ELM : external limiting membrane ETDRS : Early Treatment Diabetic Retinopathy Study FA : fluorescein angiography GCL : ganglion cell layer HFL : Henle fiber layer INL : inner nuclear layer IPL : inner plexiform layer IS : inner segment MNV : macular neovascularization nvAMD : neovascular age-related macular degeneration OCT : optical coherence tomography OCTA : optical coherence tomography angiography ONL : outer nuclear layer OPL : outer plexiform layer OS : outer segment RPE : retinal pigment epithelium.